The field of the disclosure relates generally to management of shared wireless communications, and more particularly, to wireless communication signal allocation in a shared unlicensed spectrum.
Conventional wireless communication systems may utilize unlicensed shared spectra. For example, the 2.4 GHz, 3.5 and 5 GHz frequency bands could be used for Wi-Fi, Bluetooth, Zigbee, and a range of other consumer, industrial, and medical wireless technologies. Other technology platforms also share a spectrum in other frequency ranges, and available wireless spectra will become more intensively shared as demand for wireless technologies increases. In some instances, the licensed spectra are strictly licensed to specified access technologies, and are not generally used by other access technologies within the same licensed spectrum.
Some conventional shared unlicensed spectrum technology systems utilize algorithm- and sensing-based distributed access, which enable common use of a wireless resource, despite a lack of active coordination among users. For example, typical Wi-Fi systems employ a carrier sense multiple access with collision avoidance (CSMA/CA) network multiple access method, which is also known as “listen-before-talk” (LBT), in which carrier sensing is used, but nodes attempt to avoid collisions by transmitting only when the channel is sensed to be idle (i.e., not being used). Wi-Fi devices employ a common, standards-based protocol to avoid interference among themselves and other users, which provides a substantially equal probability of access across all users in channel conditions.
However, new technologies are being introduced into the shared spectrum, which do not employ the cooperative techniques used by Wi-Fi devices. In particular, the introduction of mobile technologies utilizing Long Term Evolution (LTE), when operating in the same unlicensed spectra (LTE-U) and same geographical location, are known to interfere with existing technologies like Wi-Fi due to the centralized architecture of LTE and mobile systems where spectrum access is scheduled by the core network, instead of being coordinated with other access technologies accessing the same spectra resources. Mobile technologies utilizing LTE may dominate the access to a shared unlicensed spectrum without regard to other wireless access technologies. These non-cooperative mobile technologies can be implemented in an aggressive manner that utilizes a disproportionate share of airtime, as compared with cooperative technologies. For example, when a scheduled technology, such as LTE, competes with a technology that employs distributed coordination techniques, such as Wi-Fi, the Wi-Fi system will inherently defer to (that is, fail to transmit) the scheduled technology. In other words, the Wi-Fi system (and similar cooperative technologies) will “hear” the LTE system (or non-cooperative technologies) “talking,” and will wait their turn to access and transmit to the network. Ultimately this type of behavior will drive to an asymmetrical usage of the target spectrum resources, the LTE access technology becoming a dominant user of the spectrum under discussion.
Wi-Fi and other cooperative/distributed technologies are thus at an inherent disadvantage in the shared spectrum, and will experience significant interference, degraded performance, and user experience when forced to compete with non-cooperative technologies as compared with when co-existing with other 802.11 access nodes. Hardware changes to Wi-Fi devices and access points (APs) have been proposed as embedded solutions to detect the non-cooperative (aggressor) signals, but such hardware changes are expensive, and would exclude existing Wi-Fi devices since retro-fitting existing 802.11 nodes is prohibitive in operation.
Licensed-Assisted Access (LAA), which is part of the LTE-U family (also referred to as LAA LTE), presents particular coexistence challenges within a shared spectrum. LAA LTE, for example, specifies both contiguous and noncontiguous multi-carrier allocations in the non-licensed 5 GHz bands. Introduction of LAA LTE has significantly increased the traffic throughput of LTE, and impacts the ability of 802.11ac access nodes to execute channel bonding.